Scientists of the University of Antwerp and University of Liège (Belgium) have found how the human brain changes and adapts to weightlessness after being in space for six months. Some of the changes turned out to be lasting—even after eight months back on Earth. Raphaël Liégeois, soon to be the third Belgian in space, acknowledges the importance of the research "to prepare the new generation of astronauts for longer missions."

A child who learns not to drop a glass on the floor, or a tennis player predicting the course of an incoming ball to hit it accurately are examples of how the brain incorporates the physical laws of gravity to optimally function on Earth. Astronauts who go to space reside in a weightless environment, where the brain's rules about gravity are no longer applicable.

A new study on brain function in cosmonauts has revealed how the brain's organization is changed after a six-month mission to the International Space Station (ISS), demonstrating the adaptation that is required to live in weightlessness. The findings are published in the journal Communications Biology.

The University of Antwerp has been leading this BRAIN-DTI scientific project through the European Space Agency. Magnetic resonance imaging (MRI) data were taken from 14 astronaut brains before and several times after their mission to space. Using a special MRI technique, the researchers collected the astronauts' brain data in a resting condition, hence without having them engage in a specific task. This resting-state functional MRI technique enabled the researchers to investigate the brain's default state and to find out whether this changes or not after long-duration spaceflight.

Learning effect

In collaboration with the University of Liège, recent analyses of the brain's activity at rest revealed how functional connectivity, a marker of how activity in some brain areas is correlated with the activity in others, changes in specific regions.

"We found that connectivity was altered after spaceflight in regions which support the integration of different types of information, rather than dealing with only one type each time, such as visual, auditory, or movement information," say Steven Jillings and Floris Wuyts (University of Antwerp).

"Moreover, we found that some of these altered communication patterns were retained throughout eight months of being back on Earth. At the same time, some brain changes returned to the level of how the areas were functioning before the space mission."

Both scenarios of changes are plausible: retained changes in brain communication may indicate a learning effect, while transient changes may indicate more acute adaptation to changed gravity levels.

"This dataset is so special as their participants themselves. Back in 2016, we were historically the first to show how spaceflight may affect brain function on a single cosmonaut. Some years later we are now in a unique position to investigate the brains of more astronauts, several times. Therefore, we are deciphering the potential of the human brain all the more in confidence," says Dr. Athena Demertzi (GIGA Institute, University of Liège), co-supervisor of this this work.

New generation of astronauts

"Understanding physiological and behavioral changes triggered by weightlessness is key to plan human space exploration. Therefore, mapping changes of brain function using neuroimaging techniques as done in this work is an important step to prepare the new generation of astronauts for longer missions," says Raphaël Liégeois, doctor of engineering science (ULiège) with a thesis in the field of neuroscience, future ESA Astronaut.

The researchers are excited with the results, though they know it is only the first step in pursuing our understanding of brain communication changes after space travel. For example, we still need to investigate what the exact behavioral consequence is for these brain communication changes, we need to understand whether longer time spent in outer space might influence these observations, and whether brain characteristics may be helpful in selecting future astronauts or monitoring them during and after space travel.